How the Test is Performed

How to Prepare for the Test

Your health care provider may ask you to stop taking medicines that may affect the test, such as:

Bethanechol

Birth control pills

Cholinergic medications

Codeine

Indomethacin

Meperidine

Methacholine

Morphine

Thiazide diuretics

How the Test Will Feel

You may feel slight pain on a sting when the needle is inserted to draw blood. There may be some throbbing at the site after the blood is drawn. Veins and arteries vary in size so it may be harder to take a blood sample from one person than another.